Cadenya
Paid
Developers building agentic workflows
Worlds
FreemiumAPI
Agent transcripts lie — they tell you what the agent said it did, not what actually changed in your Stripe account at 2am when the retry loop ran twice and issued a double refund. Worlds exists to close that gap.
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Pricing
- Free Tier
- Free internal testing during public beta
Summary
Worlds spins up a sealed twin of the external systems your agent touches — Stripe and Zendesk in the current beta — seeds it to a known state, lets your agent run against it using its existing SDK with no code changes, then diffs what changed against what should have changed. You can inject rate limits, 500s, dropped webhooks, and expired keys to find out whether your retry logic refunds twice before that happens in production. You can also advance a logical clock to drive subscription renewals, prorations, and cancellations through their full cycle. Coverage beyond Stripe and Zendesk is not yet available, which is the hard ceiling for teams whose agents touch Salesforce or Okta today.
Bottom line: Worlds is the right call for teams building agents that write to Stripe or Zendesk and need outcome-level proof rather than transcript-level reassurance — but if your agent also touches Salesforce, Okta, or Shopify, you are testing the interesting half of your workflow in a sandbox that does not yet exist.
Find your fit
Before you choose Worlds
More options in Agent Frameworks. Compare pricing, platforms, and features side by side.
Brain Memory
Free · Open source
Long-term continuity in multi-session coding projects
Pros
- Identical, millisecond-ready starting states for every test run, so flaky results caused by leftover data from a previous run stop masking real bugs.
- Outcome diffing in dollars and object-level changes rather than transcript review, which means a double-refund or missed cancellation shows up as a specific line item rather than a vague 'the agent seemed to succeed'.
- Injected failures — rate limits, 500 errors, dropped webhooks, expired keys — applied to a controlled environment, so you find out whether your retry logic charges twice before a real customer does.
- Logical clock that advances subscription time on demand, so billing edge cases like proration, trial expiry, and renewal webhook ordering are testable in minutes rather than requiring calendar time or fragile date mocks.
- Agent points at the world using its existing SDK with no code changes, so integration into a current test suite does not require a parallel implementation of your agent's API layer.
Cons
- Connector coverage is limited to Stripe and Zendesk in the beta. Teams whose agents also write to Salesforce, Okta, Shopify, or Guidewire — all shown in the catalog — cannot test those interactions with Worlds yet. Those teams either run partial coverage and accept the gap, or continue using vendor sandboxes for the unsupported connectors, which reintroduces the inconsistent-state problem Worlds is built to solve.
- No self-hosted option is available. Teams operating under data residency requirements or in air-gapped environments cannot use Worlds regardless of how well it fits the use case — those teams evaluate alternatives that support on-premises deployment.
- The free tier is explicitly tied to the beta period. Post-beta pricing is not disclosed on the vendor page, which means teams building a testing pipeline on top of Worlds are accepting future cost uncertainty before the tool's pricing structure is set.
About
- Platforms
- Web
- API Available
- Yes
- Self-Hosted
- No
- Last Updated
- September 30, 2026
Best For
Who it's for
- Teams building agents that interact with Stripe or Zendesk
- Evaluating agent reliability in production-like conditions
- Debugging state changes and side effects
- Compliance and audit of agent behavior
What it does well
- Verify agent actions by comparing system state before and after runs
- Test retry logic and error handling with injected failures
- Simulate time passage for billing and renewal workflows
- Grade agent performance on actual outcomes rather than transcripts
- Run repeatable tests on identical starting states
Integrations
Frequently Asked Questions
- Is Worlds free?
- Worlds offers a free option alongside paid upgrades. Check the current allowances and terms before choosing a plan.
- Does Worlds have an API?
- Yes. Worlds exposes a developer API. See the official documentation at https://usesparta.co for details.
- When was Worlds released?
- Worlds was first released in 2026.
- What platforms does Worlds support?
- Worlds is available on: Web.
Curated lists that include this category
Transcripts hide the real damage
Agent transcripts lie. They report what the agent claimed to do, not the double refund that hit Stripe when a retry loop ran twice at 2 a.m. Worlds creates a sealed copy of Stripe and Zendesk, resets it to a known starting state, and lets the agent run with its normal SDK. After the run it shows exactly which objects changed and by how much.
How it works
The vendor states you can inject rate limits, 500 errors, dropped webhooks, and expired keys to test retry behavior before production. A logical clock advances time so subscription renewals, prorations, and cancellations complete their full cycle. Every test starts from an identical clean state, removing the flaky data that usually masks bugs.
Current limits
Only Stripe and Zendesk connectors exist in the beta. No self-hosted option is offered. The vendor states the tool is free for internal testing during the public beta.
Who it is for / who should skip it
Teams that need repeatable tests of agent actions against Stripe or Zendesk and want outcome diffs instead of transcript review should try it. Teams whose agents also touch Salesforce, Okta, Shopify, or Guidewire, or that require self-hosted or air-gapped deployment, should skip it until coverage expands.
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